1. Field of the Invention
The present invention relates to an exhaust gas-purifying catalyst.
2. Description of the Related Art
Many automotive vehicles such as automobiles are equipped with a three-way catalyst as an exhaust gas-purifying catalyst. The three-way catalyst contains precious metals as catalytic metals. The precious metals promote the oxidation reactions of hydrocarbons (HC) and carbon monoxide (CO) and the reductive reactions of nitrogen oxides (NOx).
Jpn. Pat. Appln. KOKAI Publication Nos. 63-116741, 01-242149, and 10-202101 describe exhaust gas-purifying catalysts containing a composite oxide of cerium oxide and zirconium oxide and a precious metal supported by the composite oxide. In these exhaust gas-purifying catalysts, the composite oxide is an oxygen storage material having an oxygen storage capacity. The oxygen storage material can optimize the above-described reductive reactions and oxidation reactions.